It all kicked off at Chloe Sims' birthday party after Kate, Amber Dowding and Georgia Kousoulou bumped into Jon and Chris Clark at the gift table.
Georgia questioned the guys on whether they'd got Chloe a present, but seeing Jon's face, said: "What's wrong with you? You look like you're going to kill someone sometimes..."
Kate then said: "Sometimes I think you're actually really nice and happy, and sometimes you're really angry. I don't understand."
"You being the person to tell me that is pretty f**king ironic, to be honest," replied Jon.
Kate hit back saying: "I thought we patched that over! I haven't got an issue at all. I know you've been saying to Georgia things like, 'Oh Kate, is a bad influence...'"
Jon retorted: "If you want to have a go at me, sweet, I'm game. I couldn't care less what you say, Kate. You're a snake, two-faced, evil, poisonous woman."
Wow, that's pretty harsh, right?
Kate told Jon she wasn't having a go at him. He then went on to row with Amber, before Kate suggested they all walk away from each other as it was Chloe's birthday and they shouldn't ruin it.
The co-stars had drama earlier this series when Jon accused Kate of sleeping with one of his friends after her split from Dan Edgar. He also called her a "slag." She vehemently denied sleeping with anyone and accused Jon of hitting on her via voice notes after her breakup from Dan.
They did later meet to clear the air... but is that all in the past?
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